1. Field of the Invention
This invention relates to medical instruments provided with valve means, and more particularly to a medical instrument suitable for use in a catheter introducer, a general catheter, a catheter with a balloon, an ectosomatic circulating device and the like.
2. Description of the Prior Art
There has heretofore been used a catheter introducer for medical treatment as a means for introducing rod-like members such for example as a catheter for blood-vessel contrast and the like into a blood-vessel. In a method of introducing a catheter using a catheter introducer into a blood-vessel, firstly, a hollow needle inserted therethrough with an inner needle penetrates through a skin and is introduced into the blood-vessel, subsequently, and a guide wire is inserted through the hollow needle, from which the inner needle is removed, and thereafter, the hollow needle is removed and only the guide wire is left behind. Subsequently, a main body of the introducer inserted therethrough with an expander is advanced into the blood-vessel through the guide wire, thereafter, the dilator together with the guide wire, and the catheter is guided into a path in a main body so as to be insertable into the blood-vessel.
In the catheter introducer for medical treatment as described above, when the catheter is inserted into a path of the main body of the introducer and when the catheter is not inserted, in order to prevent a blood flow to the outside through the path of the main body of the introducer, it is necessary to provide a valve body in the path of the main body of the introducer.
In FIGS. 1 and 2, designated at reference numeral 1 is a catheter introducer for medical treatment, 2 a main body, 3 a cap, and 4 a catheter. In this catheter introducer 1, a first valve body 5 and a second valve body 6, which are made of an elastomeric material, are parallelly provided in a path 2A of the main body 2 in a manner to be clamped by the main body 2 and the cap 3. The first valve body 5 is provided at the central portion thereof with a round opening 5A, and makes it possible to prevent a blood leak under conditions where the catheter 4 is inserted into the path of the main body 2. The second valve body 6 is provided at the central portion there of with a slit 6A, and makes it possible to prevent a blood leak when the catheter 4 is not inserted through the path of the main body 2.
However, a valve body assembly comprising the first valve body 5 and the second valve body 6, an outer diameter of the catheter 4 which is applicable is primarily fixed as commensurate to the round opening 5A formed on the first valve body. In consequence, when only the guide wire is inserted and held in the first valve body 5 and the second valve body 6, a blood leak cannot be prevented, and it becomes difficult to apply to a forward end flexing type catheter requiring a combination of the catheter introducer 1 with the guide wire. Furthermore, in removing the catheter 4 inserted in the main body 2, if the catheter 4 is abruptly withdrawn, then there is a possibility that the slit 6A does not immediately form a suitable closed state and a blood flow-out occurs. Furthermore, this valve body assembly, consisting of the two valve bodies including the first valve body 5 and the second valve body 6, becomes complicated in construction.
In another catheter introducer for medical treatment of the prior art, which has been proposed in Japanese patent application No. 178915/81 (Patent Kokai (Laid-Open) No. 110262/82), such a valve body assembly is used which includes a disc-shaped first valve body having an expandable opening, by which no materials are removed, and a tubular second valve body provided with a forward end portion having sealing lips which are pressed against each other. However, the valve body assembly, being small in scope of expansion or contraction of the opening provided in the first valve body, cannot have tubular members of widely varied outer diameters inserted therethrough and held therein. Furthermore, the valve body assembly, consisting of the two valve bodies including the first valve body and the second valve body, becomes complicated in construction.
In view of the problems accompanied with the prior art, the present inventors have proposed a valve body having a first slit openable in one of the end faces and a second slit openable in the other of the end faces, the first slit and the second slit crossing each other in the valve body (UK patent application No. 2135889A). Since this valve body is dispensed with a first valve 5 having ring-shaped disk as shown in FIG. 1, a catheter of various outer diameters can be applicable thereto without causing leakage of blood. However this valve body has a drawback in that it will take a relatively long time to restore its original closed status after the withdrawal of a catheter, so that a small amount of blood may leak out of the valve body. This tendency is more apparent when a catheter is left in the valve for a long period of time.